Alan Thicke's Official Cause of Death Revealed

The Canadian actor died of a "ruptured aorta" and a "standard type A aortic dissection," according to his official death certificate, which ET obtained on Wednesday. The death certificate lists the time interval between the onset of the ruptured aorta and his death as minutes, while the time between the onset of the aortic dissection and his
death is listed as three hours.

A median sternotomy was performed on Thicke on Dec. 13 -- a surgical procedure in which a vertical incision is made along the sternum, providing access to the heart and lungs -- though Thicke did not survive. His time of death is listed as 2:14 p.m. on the same day.

A type A aortic dissection is a tear beginning in the ascending aorta which progresses throughout the vessel. Symptoms include a sudden onset of severe chest or back pain, and may include vomiting, sweating and lightheadedness.

Thicke was initially vomiting and not feeling well prior to his death -- when he was playing hockey with his 19-year-old son, Carter, at the Pickwick Gardens ice skating rink in Burbank, California -- Pickwick Gardens vice president Darin Mathewson told ET last Thursday. Still, Mathewson -- who placed the 911 call when Thicke collapsed at the rink -- said the Growing Pains star was "coherent" when emergency personnel arrived, and was moving around and speaking to his son.

"He said he had pain in his chest, but his color was not good," Mathewson said. "He was a little gray. When the ambulance got here they checked his vitals ... and they put him on the gurney, sat him up."

"When he went by us, he gave us the thumbs up, like, 'I'm doing good guys, I'm good,'" he added.

The beloved Canadian actor's son, 39-year-old singer Robin Thicke, hosted a star-studded memorial to his father on Sunday. A source told ET that about 150 people attended the emotional memorial service that took place at Thicke's ranch in Carpinteria, California, including Leonardo DiCaprio, Bob Saget, Kevin Costner, and the entire cast of Growing Pains.